Ham and Cheese
I took these at f/1.8 on purpose to throw the background out of focus. I also got in really tight to his face so that I'd get a lot of perspective distortion which plays well with all his mugging for the camera. But when you combine a really big aperture with a really short subject distance, the resulting depth of field is only going to be a few millimeters deep! So only the nearest eye is sharp. In retrospect, I should have a stopped down just enough to get both eyes really sharp.
And this is exactly why you have to shoot as much as possible, The more mistakes you make, the better you get. That is, as long as you're evaluating everything afterwards with an attitude of, "How can I make this better?"